Autonomous control of a parafoil recovery system for UAVs

ABSTRACT

A parafoil system for autonomously controlling the gliding descent of a payload/UAV from a launch point to a predetermined recovery area and manipulating the parafoil to execute a soft landing in the recovery area, a sensing means associated with the system for determining wind speed and direction, as well as altitude, heading and position of the system, a means housed within the system for processing information received from the sensing means to determine the gliding flight path from the launch point to a predetermined recovery area and the execution of a flare maneuver to achieve a soft landing, control surface means on the parafoil canopy, mechanical means coupling the information processing means with the control surface means for adjusting the control surface means to accomplish the steering to the recovery area during gliding flight and the flare maneuver during landing, and a power source in the payload/UAV.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an apparatus for the parachuterecovery of a payload. More particularly to an autonomous steering of aparafoil recovery system to a recovery area and the soft landing of thepayload.

[0003] 2. Description of the Related Art

[0004] Current parachute recovery systems use an uncontrolled round (orballistic) parachute. The parachute descends at a vertical speeddepending on the relation of the size of the parachute to the weight ofthe payload. The system also has a horizontal speed and direction equalto that of the surface wind. The round parachute system drifts with thewind and impacts the ground at a random orientation. This ground impactusually results in damage to the payload due to the vertical descentrate and the horizontal speed which causes the payload to tumble and/orslam into rocks, trees, etc. In addition, since the round parachute isdifficult to steer and drifts with the wind, the ground impact locationis random.

[0005] Clearly there is a need for a parachute recovery system that canbe steered to a precise recovery area and then execute a soft landing,all autonomously.

[0006] The related art teaches several parachute recovery systems forthe controlled steering of the system to a predetermined recovery area,but none include the soft landing offered by the present invention. Forexample U.S. Pat. No. 5,201,482 to Ream, U.S. Pat. No. 5,620,153 toGinsberg and U.S. Pat. No. 5,899,415 to Conway all use parafoils (or ramair parachutes) for controlling the glide path of the recovery system.These systems all rely on human piloting of the parafoil (i.e.;non-autonomous). U.S Pat. No. 6,122,572 to Yavnai, teaches an autonomouscommand and control unit for a powered airborne vehicle that uses aprogrammable decision unit capable of managing and controlling theexecution of a mission by using subsystems and a data base capable ofholding and manipulating data including prestored data and data acquiredby and received from the various subsystems. U.S. Pat. No. 6,144,899 toBabb et al. discloses a recoverable airborne winged instrument platformfor use in predicting and monitoring weather conditions. The platform istaken aloft by balloon mean, accurately determines its present positionand uses the data to execute a predetermined flight plan and ultimatelyguide its descent to a predetermined landing site. This is achieved byinstalling the instrument package payload in the aerodynamic exteriorhousing of the recoverable airborne instrument platform.

[0007] Against this background of known technology, the applicant hasdeveloped a novel system of components for autonomously managing andcontrolling a parafoil recovery system to a preselected recovery areaand then executing a soft landing.

OBJECTS AND SUMMARY OF THE INVENTION

[0008] It is therefore an object of the present invention to provide anovel system for the autonomous control of the gliding descent of aparafoil recovery system to steer to a predetermined recovery area,while overcoming many of the disadvantages and drawbacks of similarconfigurations known in the art.

[0009] Another object of the present invention is to autonomouslymanipulate the parafoil recovery system to execute a soft landing (i.e.;reduce the vertical and horizontal speeds at ground impact relative toan uncontrolled parafoil landing) at the recovery site.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a schematic diagram depicting the parafoil and theattached payload of the present invention;

[0011]FIG. 2 is a schematic diagram depicting the control hardware inthe payload of the present invention;

[0012]FIG. 3 is a functional diagram of the control system contained inthe payload of the present invention;

[0013]FIG. 4 is a block diagram showing the chronology of functionsperformed by the autonomous control embodied by the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The following description is provided to enable any personskilled in the art to make and use the invention and sets forth the bestmodes contemplated by the inventor of executing his invention. Variousmodifications, however will be readily apparent to those skilled in theart, since the generic principles of the present invention have beendefined herein specifically to provide a control system for a parafoilthat replicates a human operator as the payload, and which encompassesmany long sought after features that make the present invention mostdesirable when used in the parachute recovery of payloads.

[0015] Referring to the schematic diagram of FIG. 1, the parafoilrecovery system includes the rectangular shaped, ram-air filled parafoilcanopy 12, leading edge 11, railing edge 22 and sides 18 and 18″ of saidcanopy, the main risers 13 that connect the canopy leading edge andsides to the payload, the brake line risers 14R and 14L that connect theouter portion (left and right) of the trailing edge to the brake reelmotors 20R and 20L, the payload 10 (shown here as an unmanned aerialvehicle UAV), and the payload attitude lines 16R and 16L which controlthe attitude (nose up or nose down) of the payload during descent.

[0016] Referring to FIG. 2 (a schematic diagram of the hardware items inthe payload), the parafoil main risers 13 are collected at the parafoilrelease mechanisms 15R and 15L (releases the payload from the parafoilupon ground impact so that the payload is not dragged across the groundby surface winds) which are connected to the payload attach points 21Rand 21L, and the reel motors 20R and 20L which connect to brake linerisers 14R and 14L and reel the brake line risers in or out to controlthe outer portion of the canopy trailing edge.

[0017]FIG. 3 shows a functional diagram of the control system whichconsists of the IVMC (integrated vehicle management computer) 30, theright and left reel motors 20R and 20L, the GPS antenna 34, the AGL(height above ground level) sensors 35, and the 28 vdc power supply 36.The IVMC contains the motor controller 31, the computer 32, the GPSreceiver 33, and the heading indicator (compass) 37.

[0018]FIG. 4 schematically illustrates the step-by-step method by whichthe control system is executed. The parafoil is deployed from thepayload and stabilized in an equilibrium glide in blocks 41 and 42. Themain risers are rigged and reel motors are adjusted before launch sothat all lines are of the proper length to give this equilibrium glide.In block 43 the location of the recovery system is determined using GPSand a flight plan developed to steer to the stored coordinates of therecovery area. This plan is continually updated to account for winds asthe system glides to the recovery area.. When over the recovery area asignal is sent to one reel to adjust the parafoil trailing edge for aspiral flight path in block 44. The spiral flight path permits thecomputer to determine the wind speed and direction in block 45. The winddirection is needed since the parafoil recovery system always wants toland into the wind in order to reduce the horizontal speed and eliminatethe possibility of a sideways or tail first ground impact. In block 46the computer determines the last spiral and the appropriate time to comeout of the spiral for landing into the wind. At 50 feet above groundlevel the recovery system is prepared for landing by reverting to a veryaccurate altimeter (±1 foot accuracy). At a TBD altitude AGL a signal issent to both reel motors in block 50 to reel in the brake lines andapply partial brakes in order to flare the parafoil and reduce thevertical descent speed from ˜27 ft/sec to ˜5 ft/sec. In block 51 thecomputer determines the ground speed using GPS and determines the extentof the braking (from none to full) to reduce the horizontal speed to 5ft/sec or less. The payload impacts the ground nose first and slides toa stop.

What I claim is :
 1. A system for autonomously controlling the glidepath and flare landing of a parafoil recovery system for the recovery ofan airborne payload from a launch point to a predetermined recoveryarea, comprising: a parafoil canopy coupled to said payload, saidparafoil canopy having a flexible leading edge and a flexible trailingedge, said trailing edge having a control surface; sensing meansassociated with said system for determining wind speed and direction, aswell as altitude, heading and position of said system, means housedwithin said payload of the said recovery system for continuouslyprocessing information received from said sensing means to determine theglide flight path from the launch point to said recovery area and flarelanding maneuver to enable a soft landing, control surface means on saidtrailing edge of the said recovery system; mechanical means couplingsaid information processing means with said control surface meansrelative to the trailing edge of said parafoil recovery system powersource means in said payload, whereby adjustment of said control surfacemeans is performed on a continuous basis throughout the gliding flightof said recovery system from launch to said recover area.
 2. The glidingpath and flare maneuver controlling system of claim 1, wherein saidmechanical means comprises spool means on said payload and control lineswrapped about said spool means and attached at one end to said trailingedge control surfaces.
 3. The gliding path and flare maneuvercontrolling means of claim 2, and further comprising motors functionallycoupled with said processing means and said spool means, for drivingsaid spools in one of a forward winding rotation or a rearward unwindingrotation, whereby as said flight path is determined, adjustments to saidcontrol surfaces are made on a continuing basis until the payloadimpacts the recovery area.
 4. The gliding flight path and flare maneuvercontrolling means of claim 3, wherein said control surfaces comprisesaid flexible trailing edge of said parafoil canopy.